The present invention relates generally to signaling in a GSM communication system, and in particular, the present invention relates to a method for receipt of paging messages from a packet-switched data domain while a mobile station is in a dedicated mode circuit-switched voice connection.
Global System for Mobile Communications (GSM) General Packet Radio Service (GPRS) is intended to allow a service subscriber the ability to send and receive data in an end-to-end packet transfer mode without utilizing network resources in the circuit-switched mode. GPRS permits efficient use of radio and network resources when data transmission characteristics are i) packet based, ii) intermittent and non-periodic, iii) possibly frequent, with small transfers of data, e.g. less than 500 octets, or iv) possibly infrequent, with large transfers of data, e.g. more than several hundred kilobytes. User applications may include Internet browsers, electronic mail and so on.
The European Telecommunications Standards Institute (ETSI) GSM specifications define what is referred to as a xe2x80x9cmobile station classxe2x80x9d for GPRS mobile stations. The mobile station class specifies some of the behavior to which a mobile station must conform regarding its operation in packet mode, circuit-switched mode, or both packet and circuit-switched mode. For example, one such mobile station class is a Class A mobile station which supports simultaneous attachment, monitoring, activation, invocation and traffic flow on both circuit-switched voice and packet-switched data services. On the other hand, a Class B mobile station has been defined to support only simultaneous attachment, monitoring and activation on both circuit-switched voice and packet-switched data services, with invocation and traffic flow possible on either service on a mutually exclusive basis. Finally, a Class C mobile station is defined to support only non-simultaneous attach, i.e. mutually exclusive attach, on either circuit-switched voice or packet-switched data services.
Mobile station classes may also be assigned, or changed, either by automatic means, or in some cases by the user, subject to limitations, such as manufacturer""s options and equipment limitations. For example, a user application may have the ability to issue a command to change the mobile station class of the subscriber equipment currently in use. The mobile station classes are therefore to be treated as xe2x80x9ceffectivexe2x80x9d classes, as users may exercise some control over mobile station class identity.
Efforts are presently underway to further develop ETSI GPRS specifications to specify required channelisation and signaling techniques that allow a mobile station, having a single receiver/transmitter, to handle a simultaneous GSM voice and packet session. This effort has led to the creation of a dual transfer mode (DTM), in which both GSM voice and GPRS, or EDGE, data can be interchanged on the same radio frequency (RF). When the mobile station is operated in dual transfer mode, the operational context of the mobile station contains an active circuit-switched voice connection in dedicated mode, and an active packet-switched temporary block flow (TBF) in GPRS/EDGE packet transfer mode.
One of the problems associated with providing a Class A capable mobile station having a single transceiver is that in currently known GSM systems, a packet-switched paging message is specified to be sent from a base station subsystem to a mobile station along a paging channel (PGCH). As a result, if a packet-switched paging message is sent to the mobile station while the mobile station is engaged in a circuit-switched voice call along a traffic channel, the mobile station is unable to receive the packet-switched domain paging message, and therefore the mobile station is unable to respond to paging messages from the packet domain while in a dedicated mode circuit-switched voice connection.
Accordingly, what is needed is a method for receipt and handling of a paging message that originates from the packet-switched domain while a mobile station is engaged in a circuit-switched domain voice call.